1. Field of the Invention.
This invention relates to the control of a manually operated gear shift mechanism, and more particularly pertains to such a control for regulating the movement of the gear selector shaft.
2. Description of the Prior Art.
Front wheel drive motor vehicles of the transaxle type, wherein the engine and transmission are positioned transversely with respect to the fore and aft axis of the motor vehicle, require some means for guiding and restricting the movement of the gear selector lever. This requirement is especially acute in transaxles because of the greater distance between the shift mechanism and the gear shaft lever than in conventional in-line transmissions. Transaxle motor vehicle design requires that the transmission be located in a more forward position in the vehicle than if the vehicle were of the in-line type. Conventional motor vehicles have the manual transmission positioned immediately below the gear selector lever, which is controlled by the vehicle operator. The response of the shift mechanism to the control of the operator occurs over a relatively shorter path and therefore the operator receives a more certain correspondence between the selected position of the shift lever and the operating speed ratio than is the case with a transaxle.
Manual transaxle vehicle design requires a distance of about three or four feet between the location of the selector lever handle and the transmission that it controls. In a vehicle equipped with a transaxle and a transversely positioned engine, the transmission and engine assembly rotates about a transverse axis with respect to the chassis. Rotation of this sort occurs because of accelerations which continually occur in normal driving conditions. Movement of the gear shift mechanism that results from this rotation contributes to an uncertain indication of the relationship between the speed ratio in which the transmission is operating and the position of the gear selector handle.
To maintain the conventional shifting pattern of the operator controlled gear selector lever for use with a transaxle having five speed ratios and a reverse drive ratio, the selector lever moves in a single fore and aft plane in order to engage the fifth speed ratio and the reverse drive ratio. With such an arrangement, it is possible that the selector lever can be moved from the fifth gear ratio position to the reverse drive ratio position by merely depressing the clutch pedal, which disengages the neutral clutch, and moving the selector lever forward to the reverse drive ratio position. If such a gear change is made at high speed, the transmission could sustain damage.
To avoid this problem, the reverse drive position of the selector lever and the fifth gear ratio position are placed in different planes, usually at opposite sides of the gear selector planes used for selection of the four lowest forward drive ratios. This complicates the shift pattern and adds complexity to the gear shift mechanism.